Astronomy Exam1

Astronomy Exam1 - Chapter 4 1) What is spectroscopy? What...

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Chapter 4 1) What is spectroscopy? What specific information about an object/surface can be gathered from that object/surface’s spectrum? Spectroscopy is the study of the way in which atoms absorb and emit electromagnetic radiation. It also allows astronomers to determine the chemical composition of stars. An object/surface’s spectrum tells us the temperature, chemical composition, radical motion, and whether it has a strong magnetic field. 2) What are Kirchhoff’s Laws? What do they describe? Kirchhoff’s Laws are three rules governing the formation of different types of spectra. 1. A luminous solid or liquid or a sufficiently dense gas emits light of all wavelengths and so produces a continuous spectrum of radiation. 2. A low-density, hoy gas emits light whose spectrum consists of a series of bight emission lines that are characteristic to the chemical composition of the gas. 3. A cool, thin gas absorbs certain wavelengths from a continuous spectrum, leaving dark absorption lines in their place, superimposed on the continuous spectrum. These lines are characteristic of the intervening gas- they occurs at precisely the same wavelengths as the emission lines produced by that gas at higher temperatures. 3) What is a photon? What are the ways in which photons interact with a surface? Photons are “packets” of electromagnetic radiation that carry a specific amount of energy. Light is emitted and absorbed in the form of photons. “Deep red” photon has half the energy of a “violet” photon. Photons can interact with a surface by reflection, scattering, transmission, absorption, and emission. Reflection- smooth surfaces relative to wavelength, energy is reflected from the surface an angle equal and opposite the incidence angle Scattering- caused by rough surfaces relative to wavelength, deflection of energy in multiple directions Transmitted- caused by a change in density (and thus velocity of the incident wave) between two materials, energy passes through the material (index of refraction)
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This note was uploaded on 02/15/2012 for the course ACCT 109 taught by Professor Tee during the Spring '12 term at Pitt CC.

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Astronomy Exam1 - Chapter 4 1) What is spectroscopy? What...

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